Ten patients with one or more ureteral tumors were examined with CT. The tumor was clearly recognizable as a soft tissue mass (average density 46 HU) filling the ureter in nine of the patients. In five of these patients the tumor was not detected by urography. Tumors <5 mm in diameter were missed on CT in one patient. Although most ureteral tumors are detectable with urography and retrograde pyelography, CT can be a valuable diagnostic tool. Computed tomography is particularly advantageous in patients with nonfunctioning kidneys and in those in whom retrograde pyelography is unsuccessful. © Raven Press, New York.